diff --git a/main.go b/main.go
index 344433f..cb4a9ac 100644
--- a/main.go
+++ b/main.go
@@ -121,6 +121,7 @@ func main() {
 		localProxyAddr       string
 		localProxyPort       int
 		localOverridesStr    string
+		trustedUpstreamsStr  string
 		proxyProtocol        bool
 	)
 
@@ -138,6 +139,7 @@ func main() {
 	localProxyAddr = os.Getenv("LOCAL_PROXY")
 	localProxyPortStr := os.Getenv("LOCAL_PROXY_PORT")
 	localOverridesStr = os.Getenv("LOCAL_OVERRIDES")
+	trustedUpstreamsStr = os.Getenv("TRUSTED_UPSTREAMS")
 	proxyProtocolStr := os.Getenv("PROXY_PROTOCOL")
 
 	if interfaceName == "" {
@@ -197,6 +199,9 @@ func main() {
 	if localOverridesStr != "" {
 		flag.StringVar(&localOverridesStr, "local-overrides", "", "Comma-separated list of local overrides for SNI proxy")
 	}
+	if trustedUpstreamsStr == "" {
+		flag.StringVar(&trustedUpstreamsStr, "trusted-upstreams", "", "Comma-separated list of trusted upstream proxy domain names/IPs that can send PROXY protocol")
+	}
 
 	if proxyProtocolStr != "" {
 		proxyProtocol = strings.ToLower(proxyProtocolStr) == "true"
@@ -323,7 +328,16 @@ func main() {
 		logger.Info("Local overrides configured: %v", localOverrides)
 	}
 
-	proxySNI, err = proxy.NewSNIProxy(sniProxyPort, remoteConfigURL, key.PublicKey().String(), localProxyAddr, localProxyPort, localOverrides, proxyProtocol)
+	var trustedUpstreams []string
+	if trustedUpstreamsStr != "" {
+		trustedUpstreams = strings.Split(trustedUpstreamsStr, ",")
+		for i, upstream := range trustedUpstreams {
+			trustedUpstreams[i] = strings.TrimSpace(upstream)
+		}
+		logger.Info("Trusted upstreams configured: %v", trustedUpstreams)
+	}
+
+	proxySNI, err = proxy.NewSNIProxy(sniProxyPort, remoteConfigURL, key.PublicKey().String(), localProxyAddr, localProxyPort, localOverrides, proxyProtocol, trustedUpstreams)
 	if err != nil {
 		logger.Fatal("Failed to create proxy: %v", err)
 	}
diff --git a/proxy/proxy.go b/proxy/proxy.go
index 7c7b078..e2e0c73 100644
--- a/proxy/proxy.go
+++ b/proxy/proxy.go
@@ -11,6 +11,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -31,6 +32,16 @@ type RouteAPIResponse struct {
 	Endpoints []string `json:"endpoints"`
 }
 
+// ProxyProtocolInfo holds information parsed from incoming PROXY protocol header
+type ProxyProtocolInfo struct {
+	Protocol     string // TCP4 or TCP6
+	SrcIP        string
+	DestIP       string
+	SrcPort      int
+	DestPort     int
+	OriginalConn net.Conn // The original connection after PROXY protocol parsing
+}
+
 // SNIProxy represents the main proxy server
 type SNIProxy struct {
 	port            int
@@ -55,6 +66,9 @@ type SNIProxy struct {
 	// Track active tunnels by SNI
 	activeTunnels     map[string]*activeTunnel
 	activeTunnelsLock sync.Mutex
+
+	// Trusted upstream proxies that can send PROXY protocol
+	trustedUpstreams map[string]struct{}
 }
 
 type activeTunnel struct {
@@ -75,6 +89,159 @@ func (conn readOnlyConn) SetDeadline(t time.Time) error      { return nil }
 func (conn readOnlyConn) SetReadDeadline(t time.Time) error  { return nil }
 func (conn readOnlyConn) SetWriteDeadline(t time.Time) error { return nil }
 
+// parseProxyProtocolHeader parses a PROXY protocol v1 header from the connection
+func (p *SNIProxy) parseProxyProtocolHeader(conn net.Conn) (*ProxyProtocolInfo, net.Conn, error) {
+	// Check if the connection comes from a trusted upstream
+	remoteHost, _, err := net.SplitHostPort(conn.RemoteAddr().String())
+	if err != nil {
+		return nil, conn, fmt.Errorf("failed to parse remote address: %w", err)
+	}
+
+	// Resolve the remote IP to hostname to check if it's trusted
+	// For simplicity, we'll check the IP directly in trusted upstreams
+	// In production, you might want to do reverse DNS lookup
+	if _, isTrusted := p.trustedUpstreams[remoteHost]; !isTrusted {
+		// Not from trusted upstream, return original connection
+		return nil, conn, nil
+	}
+
+	// Set read timeout for PROXY protocol parsing
+	if err := conn.SetReadDeadline(time.Now().Add(5 * time.Second)); err != nil {
+		return nil, conn, fmt.Errorf("failed to set read deadline: %w", err)
+	}
+
+	// Read the first line (PROXY protocol header)
+	buffer := make([]byte, 512) // PROXY protocol header should be much smaller
+	n, err := conn.Read(buffer)
+	if err != nil {
+		return nil, conn, fmt.Errorf("failed to read PROXY protocol header: %w", err)
+	}
+
+	// Find the end of the first line (CRLF)
+	headerEnd := bytes.Index(buffer[:n], []byte("\r\n"))
+	if headerEnd == -1 {
+		return nil, conn, fmt.Errorf("PROXY protocol header not found")
+	}
+
+	headerLine := string(buffer[:headerEnd])
+	remainingData := buffer[headerEnd+2 : n]
+
+	// Parse PROXY protocol line: "PROXY TCP4/TCP6 srcIP destIP srcPort destPort"
+	parts := strings.Fields(headerLine)
+	if len(parts) != 6 || parts[0] != "PROXY" {
+		// Check for PROXY UNKNOWN
+		if len(parts) == 2 && parts[0] == "PROXY" && parts[1] == "UNKNOWN" {
+			// PROXY UNKNOWN - use original connection info
+			return nil, conn, nil
+		}
+		return nil, conn, fmt.Errorf("invalid PROXY protocol header: %s", headerLine)
+	}
+
+	protocol := parts[1]
+	srcIP := parts[2]
+	destIP := parts[3]
+	srcPort, err := strconv.Atoi(parts[4])
+	if err != nil {
+		return nil, conn, fmt.Errorf("invalid source port in PROXY header: %s", parts[4])
+	}
+	destPort, err := strconv.Atoi(parts[5])
+	if err != nil {
+		return nil, conn, fmt.Errorf("invalid destination port in PROXY header: %s", parts[5])
+	}
+
+	// Create a new reader that includes remaining data + original connection
+	var newReader io.Reader
+	if len(remainingData) > 0 {
+		newReader = io.MultiReader(bytes.NewReader(remainingData), conn)
+	} else {
+		newReader = conn
+	}
+
+	// Create a wrapper connection that reads from the combined reader
+	wrappedConn := &proxyProtocolConn{
+		Conn:   conn,
+		reader: newReader,
+	}
+
+	proxyInfo := &ProxyProtocolInfo{
+		Protocol:     protocol,
+		SrcIP:        srcIP,
+		DestIP:       destIP,
+		SrcPort:      srcPort,
+		DestPort:     destPort,
+		OriginalConn: wrappedConn,
+	}
+
+	// Clear read timeout
+	if err := conn.SetReadDeadline(time.Time{}); err != nil {
+		return nil, conn, fmt.Errorf("failed to clear read deadline: %w", err)
+	}
+
+	return proxyInfo, wrappedConn, nil
+}
+
+// proxyProtocolConn wraps a connection to read from a custom reader
+type proxyProtocolConn struct {
+	net.Conn
+	reader io.Reader
+}
+
+func (c *proxyProtocolConn) Read(b []byte) (int, error) {
+	return c.reader.Read(b)
+}
+
+// buildProxyProtocolHeaderFromInfo creates a PROXY protocol v1 header using ProxyProtocolInfo
+func (p *SNIProxy) buildProxyProtocolHeaderFromInfo(proxyInfo *ProxyProtocolInfo, targetAddr net.Addr) string {
+	targetTCP, ok := targetAddr.(*net.TCPAddr)
+	if !ok {
+		// Fallback for unknown address types
+		return "PROXY UNKNOWN\r\n"
+	}
+
+	// Use the original client information from the PROXY protocol
+	var targetIP string
+	var protocol string
+
+	// Parse source IP to determine protocol family
+	srcIP := net.ParseIP(proxyInfo.SrcIP)
+	if srcIP == nil {
+		return "PROXY UNKNOWN\r\n"
+	}
+
+	if srcIP.To4() != nil {
+		// Source is IPv4, use TCP4 protocol
+		protocol = "TCP4"
+		if targetTCP.IP.To4() != nil {
+			// Target is also IPv4, use as-is
+			targetIP = targetTCP.IP.String()
+		} else {
+			// Target is IPv6, but we need IPv4 for consistent protocol family
+			if targetTCP.IP.IsLoopback() {
+				targetIP = "127.0.0.1"
+			} else {
+				targetIP = "127.0.0.1" // Safe fallback
+			}
+		}
+	} else {
+		// Source is IPv6, use TCP6 protocol
+		protocol = "TCP6"
+		if targetTCP.IP.To4() != nil {
+			// Target is IPv4, convert to IPv6 representation
+			targetIP = "::ffff:" + targetTCP.IP.String()
+		} else {
+			// Target is also IPv6, use as-is
+			targetIP = targetTCP.IP.String()
+		}
+	}
+
+	return fmt.Sprintf("PROXY %s %s %s %d %d\r\n",
+		protocol,
+		proxyInfo.SrcIP,
+		targetIP,
+		proxyInfo.SrcPort,
+		targetTCP.Port)
+}
+
 // buildProxyProtocolHeader creates a PROXY protocol v1 header
 func buildProxyProtocolHeader(clientAddr, targetAddr net.Addr) string {
 	clientTCP, ok := clientAddr.(*net.TCPAddr)
@@ -131,7 +298,7 @@ func buildProxyProtocolHeader(clientAddr, targetAddr net.Addr) string {
 }
 
 // NewSNIProxy creates a new SNI proxy instance
-func NewSNIProxy(port int, remoteConfigURL, publicKey, localProxyAddr string, localProxyPort int, localOverrides []string, proxyProtocol bool) (*SNIProxy, error) {
+func NewSNIProxy(port int, remoteConfigURL, publicKey, localProxyAddr string, localProxyPort int, localOverrides []string, proxyProtocol bool, trustedUpstreams []string) (*SNIProxy, error) {
 	ctx, cancel := context.WithCancel(context.Background())
 
 	// Create local overrides map
@@ -142,19 +309,36 @@ func NewSNIProxy(port int, remoteConfigURL, publicKey, localProxyAddr string, lo
 		}
 	}
 
+	// Create trusted upstreams map
+	trustedMap := make(map[string]struct{})
+	for _, upstream := range trustedUpstreams {
+		if upstream != "" {
+			// Add both the domain and potentially resolved IPs
+			trustedMap[upstream] = struct{}{}
+
+			// Try to resolve the domain to IPs and add them too
+			if ips, err := net.LookupIP(upstream); err == nil {
+				for _, ip := range ips {
+					trustedMap[ip.String()] = struct{}{}
+				}
+			}
+		}
+	}
+
 	proxy := &SNIProxy{
-		port:            port,
-		cache:           cache.New(3*time.Second, 10*time.Minute),
-		ctx:             ctx,
-		cancel:          cancel,
-		localProxyAddr:  localProxyAddr,
-		localProxyPort:  localProxyPort,
-		remoteConfigURL: remoteConfigURL,
-		publicKey:       publicKey,
-		proxyProtocol:   proxyProtocol,
-		localSNIs:       make(map[string]struct{}),
-		localOverrides:  overridesMap,
-		activeTunnels:   make(map[string]*activeTunnel),
+		port:             port,
+		cache:            cache.New(3*time.Second, 10*time.Minute),
+		ctx:              ctx,
+		cancel:           cancel,
+		localProxyAddr:   localProxyAddr,
+		localProxyPort:   localProxyPort,
+		remoteConfigURL:  remoteConfigURL,
+		publicKey:        publicKey,
+		proxyProtocol:    proxyProtocol,
+		localSNIs:        make(map[string]struct{}),
+		localOverrides:   overridesMap,
+		activeTunnels:    make(map[string]*activeTunnel),
+		trustedUpstreams: trustedMap,
 	}
 
 	return proxy, nil
@@ -270,14 +454,31 @@ func (p *SNIProxy) handleConnection(clientConn net.Conn) {
 
 	logger.Debug("Accepted connection from %s", clientConn.RemoteAddr())
 
+	// Check for PROXY protocol from trusted upstream
+	var proxyInfo *ProxyProtocolInfo
+	var actualClientConn net.Conn = clientConn
+
+	if len(p.trustedUpstreams) > 0 {
+		var err error
+		proxyInfo, actualClientConn, err = p.parseProxyProtocolHeader(clientConn)
+		if err != nil {
+			logger.Debug("Failed to parse PROXY protocol: %v", err)
+			return
+		}
+		if proxyInfo != nil {
+			logger.Debug("Received PROXY protocol from trusted upstream: %s:%d -> %s:%d",
+				proxyInfo.SrcIP, proxyInfo.SrcPort, proxyInfo.DestIP, proxyInfo.DestPort)
+		}
+	}
+
 	// Set read timeout for SNI extraction
-	if err := clientConn.SetReadDeadline(time.Now().Add(5 * time.Second)); err != nil {
+	if err := actualClientConn.SetReadDeadline(time.Now().Add(5 * time.Second)); err != nil {
 		logger.Debug("Failed to set read deadline: %v", err)
 		return
 	}
 
 	// Extract SNI hostname
-	hostname, clientReader, err := p.extractSNI(clientConn)
+	hostname, clientReader, err := p.extractSNI(actualClientConn)
 	if err != nil {
 		logger.Debug("SNI extraction failed: %v", err)
 		return
@@ -291,13 +492,20 @@ func (p *SNIProxy) handleConnection(clientConn net.Conn) {
 	logger.Debug("SNI hostname detected: %s", hostname)
 
 	// Remove read timeout for normal operation
-	if err := clientConn.SetReadDeadline(time.Time{}); err != nil {
+	if err := actualClientConn.SetReadDeadline(time.Time{}); err != nil {
 		logger.Debug("Failed to clear read deadline: %v", err)
 		return
 	}
 
-	// Get routing information
-	route, err := p.getRoute(hostname, clientConn.RemoteAddr().String())
+	// Get routing information - use original client address if available from PROXY protocol
+	var clientAddrStr string
+	if proxyInfo != nil {
+		clientAddrStr = fmt.Sprintf("%s:%d", proxyInfo.SrcIP, proxyInfo.SrcPort)
+	} else {
+		clientAddrStr = clientConn.RemoteAddr().String()
+	}
+
+	route, err := p.getRoute(hostname, clientAddrStr)
 	if err != nil {
 		logger.Debug("Failed to get route for %s: %v", hostname, err)
 		return
@@ -325,7 +533,14 @@ func (p *SNIProxy) handleConnection(clientConn net.Conn) {
 
 	// Send PROXY protocol header if enabled
 	if p.proxyProtocol {
-		proxyHeader := buildProxyProtocolHeader(clientConn.RemoteAddr(), targetConn.LocalAddr())
+		var proxyHeader string
+		if proxyInfo != nil {
+			// Use original client info from PROXY protocol
+			proxyHeader = p.buildProxyProtocolHeaderFromInfo(proxyInfo, targetConn.LocalAddr())
+		} else {
+			// Use direct client connection info
+			proxyHeader = buildProxyProtocolHeader(clientConn.RemoteAddr(), targetConn.LocalAddr())
+		}
 		logger.Debug("Sending PROXY protocol header: %s", strings.TrimSpace(proxyHeader))
 
 		if _, err := targetConn.Write([]byte(proxyHeader)); err != nil {
@@ -341,7 +556,7 @@ func (p *SNIProxy) handleConnection(clientConn net.Conn) {
 		tunnel = &activeTunnel{}
 		p.activeTunnels[hostname] = tunnel
 	}
-	tunnel.conns = append(tunnel.conns, clientConn)
+	tunnel.conns = append(tunnel.conns, actualClientConn)
 	p.activeTunnelsLock.Unlock()
 
 	defer func() {
@@ -350,7 +565,7 @@ func (p *SNIProxy) handleConnection(clientConn net.Conn) {
 		if tunnel, ok := p.activeTunnels[hostname]; ok {
 			newConns := make([]net.Conn, 0, len(tunnel.conns))
 			for _, c := range tunnel.conns {
-				if c != clientConn {
+				if c != actualClientConn {
 					newConns = append(newConns, c)
 				}
 			}
@@ -364,7 +579,7 @@ func (p *SNIProxy) handleConnection(clientConn net.Conn) {
 	}()
 
 	// Start bidirectional data transfer
-	p.pipe(clientConn, targetConn, clientReader)
+	p.pipe(actualClientConn, targetConn, clientReader)
 }
 
 // getRoute retrieves routing information for a hostname
diff --git a/proxy/proxy_test.go b/proxy/proxy_test.go
index d585610..747c81d 100644
--- a/proxy/proxy_test.go
+++ b/proxy/proxy_test.go
@@ -76,3 +76,44 @@ func TestBuildProxyProtocolHeaderUnknownType(t *testing.T) {
 		t.Errorf("Expected %q, got %q", expected, result)
 	}
 }
+
+func TestBuildProxyProtocolHeaderFromInfo(t *testing.T) {
+	proxy, err := NewSNIProxy(8443, "", "", "127.0.0.1", 443, nil, true, nil)
+	if err != nil {
+		t.Fatalf("Failed to create SNI proxy: %v", err)
+	}
+
+	// Test IPv4 case
+	proxyInfo := &ProxyProtocolInfo{
+		Protocol: "TCP4",
+		SrcIP:    "10.0.0.1",
+		DestIP:   "192.168.1.100",
+		SrcPort:  12345,
+		DestPort: 443,
+	}
+
+	targetAddr, _ := net.ResolveTCPAddr("tcp", "127.0.0.1:8080")
+	header := proxy.buildProxyProtocolHeaderFromInfo(proxyInfo, targetAddr)
+
+	expected := "PROXY TCP4 10.0.0.1 127.0.0.1 12345 8080\r\n"
+	if header != expected {
+		t.Errorf("Expected header '%s', got '%s'", expected, header)
+	}
+
+	// Test IPv6 case
+	proxyInfo = &ProxyProtocolInfo{
+		Protocol: "TCP6",
+		SrcIP:    "2001:db8::1",
+		DestIP:   "2001:db8::2",
+		SrcPort:  12345,
+		DestPort: 443,
+	}
+
+	targetAddr, _ = net.ResolveTCPAddr("tcp6", "[::1]:8080")
+	header = proxy.buildProxyProtocolHeaderFromInfo(proxyInfo, targetAddr)
+
+	expected = "PROXY TCP6 2001:db8::1 ::1 12345 8080\r\n"
+	if header != expected {
+		t.Errorf("Expected header '%s', got '%s'", expected, header)
+	}
+}